A single-nucleotide polymorphism (SNP) is a base pair substitution at a specific locus in a DNA sequence responsible for differences in genetic traits, susceptibility to disease, and responsively to drug therapies. SNPs are the most common type of genetic variation and are used to quickly and easily identify heritable differences among individual plants, animals, or humans within a population. Therefore, SNP genotyping can be applied extensively to human, plants and animal genetic research. The genetic variations from SNPs between individuals are exploited in DNA fingerprinting which is used in forensic science as well.